First select the parent and scale it, that will mess up the childs scale, that's fine. Next select the parent object and apply scale, then go to the child object and clear scale, everything should be as you want it now.
First select the parent and scale it, that will mess up the childs scale, that's fine. Next select the parent object and apply scale, then go to the child object and clear scale, everything should be as you want it now.